A number of arrangement for establishing the thickness of print when the print is applied to, or transferred to a print carrier or print material are known to the art.
One method long applied in the art is based on the principle of placing the print whose thickness is to be determined on a measuring table and establishing the height of the print carrier above the table. The distance from the upper surface of the print is then established. The thickness of the print can then be established, by subtracting one set of height values from the other.
It will be obvious that such a method, adapted for the laboratory, will result in wide absolute and relative errors. In addition, it is difficult to carry out the method when determining print thicknesses in a production line.
It is also known in the art that the thickness of print applied to a print carrier in a silkscreen printer is dependent on a number of mutually different parameters, such as
(a) the pressure at which the squeegee abuts the stencil PA0 (b) the angle at which the squeegee abuts the stencil PA0 (c) the speed of relative movement between the squeegee and stencil PA0 (d) the mesh size of the stencil PA0 (e) the printing ink used PA0 (f) the viscosity of the printing ink used PA0 (g) the carrier material used.
The silkscreen operator is aware that the print can be given a thickness which at least corresponds substantially to a pre-determined thickness, by varying one or more of the aforesaid parameters. Whether or not the thickness lies within acceptable limits is normally determined ocularly by the operator, who will normally rather accept a thicker layer than necessary, in order to guarantee full coverage, than a thin layer.
Experience has shown that the thickness of print can only be determined ocularly with certain types of inks and pigments, and then only when applied to certain print carriers.